* c-decl.c (finish_struct): Move code to set DECL_PACKED after
	DECL_BIT_FIELD is alreay known.  Also inherit packed for bitfields
	regardless of their type.
	* c-common.c (handle_packed_attribute): Don't ignore packed on
	bitfields.
	* c.opt (Wpacked-bitfield-compat): New warning option.
	* stor-layout.c (place_field): Warn if offset of a field changed.
	* doc/extend.texi (packed): Mention the ABI change.
	* doc/invoke.texi (-Wpacked-bitfield-compat): Document.
	(Warning Options): Add it to the list.

cp/
	* class.c (check_field_decls): Also inherit packed for bitfields
	regardless of their type.

testsuite/
	* gcc.dg/bitfld-15.c, gcc.dg/bitfld-16.c,
	gcc.dg/bitfld-17.c,gcc.dg/bitfld-18.c: New tests.
	* g++.dg/ext/bitfield2.C, g++.dg/ext/bitfield3.C,
	g++.dg/ext/bitfield4.C, g++.dg/ext/bitfield5.C: New tests.

From-SVN: r143584